1. Field of the Invention
The present invention relates generally to a semiconductor manufacturing apparatus, and more particularly to a rotating stopper which controls the number of semiconductor device packages provided to a package unloader after the packages have passed through a marker, and to a semiconductor device marking apparatus using the stopper.
2. Description of the Related Arts
Usually, prior to delivery of semiconductor device packages to the users, one surface of the semiconductor device package, usually the front surface, is marked with an alphanumeric code indicating the function, property, type of device, number of I/O pins, speed, manufacturing date, and manufacturer of the device. An apparatus, which is used in marking the code on the front surface of the package, is referred to as a "marking apparatus". An automatic marking apparatus employing a laser as the marker has been commonly used.
FIG. 1 is a front view of a conventional semiconductor device marking apparatus. Referring to FIG. 1, a semiconductor device marking apparatus 10 comprises a package loader 20, a package provider 30, a marker 40, a brush carrier 50, and a package unloader 70. Herein, all the components are positioned on a support 12, which has a tilted front surface. The package provider 30, the marker 40, the brush carrier 50, and the package unloader 70 are installed on the tilted front surface of the support 12.
In the package loader 20, a plurality of tubes 24 are loaded on a support table 26 between two loading rods 22. Each tube 24 is filled with a predetermined number of semiconductor device packages 28. The tubes 24 which are loaded on the support table 26 are provided to the package provider 30 automatically or manually, one by one, as indicated by an arrow "A".
The semiconductor device packages 28 within the tube 24, which is provided to the package provider 30, are transferred in the direction of an arrow "B" along a transfer rail 14. Since the transfer rail 14 is tilted at a certain angle as shown in FIG. 1, the packages 28 may be transferred along the transfer rail 14 by gravity without a special driving force. Next, the semiconductor device packages 28 are marked as they pass through the marker 40. In the marking step, an alphanumeric code is marked on the front surfaces of the semiconductor device packages 28 to indicate the function, property, type of device, number of I/O pins, operational speed, manufacturing date, and manufacturer of the device. The semiconductor device packages, which have passed through the marker 40, are indicated by reference numeral "29".
The semiconductor device packages 29, which are output from the marker 40, are retained on the transfer rail 14 by the brush carrier 50. The brush carrier 50 blocks the packages 29, and when a predetermined number of semiconductor device packages 29 are loaded, the brush carrier 50 moves in the direction of an arrow "D". Then, a brush 60, which is positioned beyond the upper surface of the transfer rail 14, cleans the packages 29 by brushing the marked code on the front surfaces of the packages 29. After brushing, the brush carrier 50 moves further downward in the direction of the arrow "D" until it reaches a stopper 58, which is fixed to a stop plate 16. Next, the brush carrier 50 releases the semiconductor device packages 29 and the packages 29 are inserted into tubes 74, which are loaded on a support table 76 between two loading rods 72 of the package unloader 70. After the packages 29 entirely fill one tube 74, the loading rods 72 descend in the direction of an arrow "E" and the packages 29 fill the next tube 74. At this time, since the tubes 74 are controlled such that the lower surface of the tube 74 is coplanar with the upper surface of the transfer rail 14, the packages 29 are inserted into the tubes 74 by gravity
FIG. 2 is a front view of a brush carrier, which is used in the conventional semiconductor device marking apparatus of FIG. 1. The brush carrier 50 moves along a cylinder 51 in the direction of the arrow "D" and a roller unit 52 is connected to the cylinder 51. The roller unit 52 is also connected to a lower support plate 53. The lower support plate 53 is connected to an upper support plate 55 by a support body 54, and a clamp 56 is connected to the upper support plate 55 by springs 57 or bushings (not shown).
When the clamp 56 is in the upright position, the clamp 56 protrudes from the upper surface of the transfer rail 14 and blocks the semiconductor device packages 29, which are transferred by gravity. After a predetermined number of semiconductor device packages 29 are loaded by the blocking action of the clamp 56, the brush carrier 50 moves, and the clamp 56 transfers the packages 29 downward. Then, the marked code on the front surfaces of the packages 29 is cleaned by the operation of a brush 60, which rotates in the direction of an arrow "F". After brushing, the brush carrier 50 moves further downward until it reaches a stopper 58. When the clamp 56 contacts a terminal of the stopper 58, it is rotated clockwise to a horizontal position by the terminal of the stopper 58, as indicated by an arrow "G". When the clamp 56 is in the horizontal position, the packages 29, the motion of which was blocked by the clamp 56, are freely transferred along the transfer rail 14.
After the semiconductor device packages 29 are inserted into the tube 74 of the package unloader 70, the brush carrier 50 returns to its original position and the clamp 56 returns to the earlier upright position by the restoring force of the springs. After that, again the clamp 56 blocks the next semiconductor device packages 29.
The semiconductor device marking apparatus using the conventional brush carrier described above has several problems:
First, since the brush carrier requires the semiconductor device package to move downward in order to clean the front surface on which the alphanumeric code is marked, the outer leads of the semiconductor device package may be easily damaged.
Second, since the brush carrier has a complicated structure with many individual parts, worn-out parts need to be replaced frequently, and since the clamp is controlled by the restoring force of a spring, the spring is apt to be easily worn out.
Third, since recently the marking technique has been greatly developed such that the front surface of the package, on which the code is marked, need not be cleaned, it is sufficient that the brush carrier only control the number of semiconductor device packages provided to the tubes of the package unloader by temporarily blocking a predetermined number of semiconductor device packages transferred along the transfer rail and by providing the packages to the package unloader. That is, there are now many unnecessary procedures in the conventional semiconductor device marking apparatus.